Description
Spool Performance B58 Gen 2 Auxiliary Split Fuel System
The Spool Performance B58 Gen 2 Auxiliary Fuel System is engineered for enthusiasts pushing beyond the limits of the factory fueling system. Designed with proper fuel architecture in mind, this system separates direct injection (DI) and port injection (PI) supply to deliver stable, predictable fueling at higher power levels while maintaining OEM-like integration and ease of installation.
Every component is purpose-built to ensure long-term reliability, clean installation, and consistent performance under demanding conditions.
Why a Split DI + PI Fuel System Matters
As power increases on the B58 Gen 2 platform, sharing a single fuel feed between DI and PI introduces instability:
- DI pulse cycles can disrupt fuel pressure to PI injectors
- PI systems require boost-referenced pressure for consistency
- Higher boost levels make fuel delivery less predictable
By separating the fuel supply:
- DI and PI operate independently
- Fuel pressure remains stable and consistent
- Engine performance becomes more predictable at high power levels
Key Features
- True split DI and PI fuel supply system
- Retains OEM fuel pump top hat using precision aluminum fittings
- Plug-and-play wiring harness compatible with Reflex controller
- Dual Walbro 450 fuel pumps included
- Optional Walbro 525 fuel pump upgrade available
- Choice of standard relay or solid-state relay (PWM control)
- Compact, boost-referenced fuel pressure regulator
- Triple-layer PTFE fuel lines for maximum durability
Clean OEM-Style Installation
- No repinning or modification of factory wiring required
- Integrates directly with OEM fuel pump top hat
- Optional billet top hats available separately
- Designed for a clean, factory-like engine bay appearance
High-Quality Fuel System Components
- PTFE inner core for full fuel and ethanol compatibility
- Stainless steel reinforcement for pressure resistance
- Nylon outer layer for abrasion protection
- Built for high-heat and high-vibration environments
Scalable Performance
- Dual Walbro 450 pumps support high horsepower builds
- Optional Walbro 525 upgrade for extreme setups
- Flexible control options for precise fuel delivery
- Designed to grow with your build
Performance Benefits
- Stable and consistent fueling at high boost
- Improved reliability for high horsepower applications
- Better control of fuel pressure under load
- Supports large turbo and port injection setups
- Maintains drivability while increasing fuel capacity
FITMENT
BMW M340i / M340i xDrive (2020+)
BMW M440i / M440i xDrive (2021+)
BMW X3 M40i (2020+)
BMW X4 M40i (2020+)
Additional Notes:
- Professional installation recommended
- Designed specifically for B58 Gen 2 platforms
- Compatible with Reflex controller systems
- Ideal for high-performance street and track builds
Upgrade your B58 Gen 2 fueling system with the Spool Performance Auxiliary Split Fuel System for maximum control, reliability, and scalability as your build pushes to higher power levels.
